This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Envelop protein gp140 trimers are purified by sizing exclusion chromatography, and verified by SDS-PAGE, Native gel, Western blotting, etc;sCD4 and neutralizing antibodies are also purified by sizing exclusion chromatography and verified by SDS-PAGE. We expect to obtain some small angle x-ray scattering and diffraction data for our proteins, and just those info for immunogen design.